package com.winit.common.util;

import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.support.RequestContextUtils;
/**  
 * <p>@Description:以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.</p> 
 *
 */
public class SpringContextHolder implements ApplicationContextAware, DisposableBean{
	private static ApplicationContext applicationContext = null;

	private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		
		return applicationContext;
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(String name) {

		return (T) applicationContext.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(Class<T> requiredType) {
	
		return applicationContext.getBean(requiredType);
	}
	
	/**
	 * 从静态变量applicationContext中取得通过注解@Controller声明的Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getControllerBean(HttpServletRequest request, String beanName) {
		
		WebApplicationContext webApplicationContext = RequestContextUtils.getWebApplicationContext(request, request.getSession().getServletContext());
		
		if(webApplicationContext != null){
			return (T) webApplicationContext.getBean(beanName);
		}
		
		return null;
	}
	
	/**
	 * 从静态变量applicationContext中取得通过注解@Controller声明的Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getControllerBean(HttpServletRequest request, Class<T> requiredType) {
		
		WebApplicationContext webApplicationContext = RequestContextUtils.getWebApplicationContext(request, request.getSession().getServletContext());
		
		if(webApplicationContext != null){
			return webApplicationContext.getBean(requiredType);
		}
		
		return null;
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null.
	 */
	public static void clearHolder() {
		logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		applicationContext = null;
	}

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	public void setApplicationContext(ApplicationContext applicationContext) {
		logger.debug("注入ApplicationContext到SpringContextHolder:" + applicationContext);

		if (SpringContextHolder.applicationContext != null) {
			logger.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:"
					+ SpringContextHolder.applicationContext);
		}

		SpringContextHolder.applicationContext = applicationContext; //NOSONAR
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 */
	public void destroy() throws Exception {
		SpringContextHolder.clearHolder();
	}

}
